Geothermal ground source/water source heat exchange systems typically use fluid-filled closed loops of tubing buried in the ground, or submerged in a body of water, so as to either absorb heat from, or to reject heat into, the naturally occurring geothermal mass and/or water surrounding the buried or submerged fluid transport tubing. The tubing loop is extended to the surface and is then used to circulate one of the naturally warmed and naturally cooled fluid to an interior air heat exchange means.
Common and older design geothermal water-source heating/cooling systems typically circulate, via a water pump, a fluid comprised of water, or water with anti-freeze, in plastic (typically polyethylene) underground geothermal tubing so as to transfer geothermal heat to or from the ground in a first heat exchange step. Via a second heat exchange step, a refrigerant heat pump system is used to transfer heat to or from the water. Finally, via a third heat exchange step, an interior air handler (typically comprised of finned tubing and a fan, as is well understood by those skilled in the art) is used to transfer heat to or from the refrigerant to heat or cool interior air space.
Newer design geothermal DX heat exchange systems, where the refrigerant fluid transport lines are placed directly in the sub-surface ground and/or water, typically circulate a refrigerant fluid, such as R-22 or the like, in sub-surface refrigerant lines, typically comprised of copper tubing, to transfer geothermal heat to or from the sub-surface elements via a first heat exchange step. DX systems only require a second heat exchange step to transfer heat to or from the interior air space, typically also by means of an interior air handler. Consequently, DX systems are generally more efficient than water-source systems because less heat exchange steps are required and because no water pump energy expenditure is necessary. Further, since copper is a better heat conductor than most plastics, and since the refrigerant fluid circulating within the copper tubing of a DX system generally has a greater temperature differential with the surrounding ground than the water circulating within the plastic tubing of a water-source system, generally, less excavation and drilling is required, and installation costs are lower, with a DX system than with a water-source system.
While most in-ground/in-water DX heat exchange designs are feasible, various improvements have been developed intended to enhance overall system operational efficiencies. Several such design improvements, particularly in direct expansion/direct exchange geothermal heat pump systems, are taught in U.S. Pat. No. 5,623,986 to Wiggs; in U.S. Pat. No. 5,816,314 to Wiggs, et al.; in U.S. Pat. No. 5,946,928 to Wiggs; and in U.S. Pat. No. 6,615,601 B1 to Wiggs, the disclosures of which are incorporated herein by reference. Such disclosures encompass both horizontally and vertically oriented sub-surface heat geothermal heat exchange means, using historically conventional refrigerants, such as R-22 . The use of a refrigerant operating at higher pressures than R-22, such as R-410A, has been found to be advantageous for use in a DX system incorporating at least one of the disclosures as taught herein. R-410A is an HFC azeotropic mixture of HFC-32 and HFC-125.
DX heating/cooling systems have multiple primary objectives. The first is to provide the greatest possible operational efficiencies. This directly translates into providing the lowest possible heating/cooling operational costs, as well as other advantages, such as, for example, materially assisting in reducing peaking concerns for utility companies. A second is to operate in an environmentally safe manner by using environmentally safe components and fluids. A third is to provide an economically feasible installation means at the lowest possible initial cost, so as to enhance system payback opportunities. A fourth is to provide sub-surface installation means within the smallest surface area possible. A fifth is to increase interior comfort levels. A sixth is to increase long-term system durability, and a seventh is to facilitate ease of service and maintenance.
Historically, DX heating/cooling systems, even though more efficient than other conventional heating/cooling systems, have experienced practical limitations created by the relatively large surface land areas necessary to accommodate the sub-surface heat exchange tubing. For example, with R-22 systems, a typical land area of 500 square feet per ton of system design capacity was required in first generation designs to accommodate a shallow (within 10 feet of the surface) matrix of multiple, distributed, copper heat exchange tubes. Early generation borehole designs still required about one 50 foot, to one 100 foot, (maximum) depth wells/boreholes per ton of system design capacity, preferably spaced at least about 20 feet apart. Such requisite surface areas effectively precluded system applications in many commercial and/or high density residential applications.
The subject disclosures primarily relate to DX systems installed with vertically oriented sub-surface geothermal heat exchange means, although a means to use the subject disclosure in a lake, in a fully water saturated borehole, or the like, is also disclosed. In a DX system design, primary objectives are to increase system operational efficiency levels, to reduce installation costs, to increase interior comfort levels, to increase long-term system durability, and to facilitate ease of service and maintenance. Also, a means of installing a DX Hydronic system is disclosed, with an objective of applying DX system advantages, in lieu of conventional boiler/chiller systems, and in lieu of traditional water-source geothermal heat exchange loops, in an interior building/structure. Further, a means of improving the life and reliability of an oil separator for use in a DX system would be of significant importance. Lastly, a means for providing a “mobile” DX system, that not only provided cooling, but that also generated potable water from natural moisture in the air, would also be of value for transient applications, such as for military use and for temporary field office use (such as for temporary oil exploration and/or engineering field office and/or housing facilities, or the like).
Consequently, a means to accomplish at least one of the said primary objectives would be preferable. The present disclosure provides solutions to these preferable objectives, as hereinafter more fully described.